Feasibility of the aktivplan Digital Health Intervention for Regular Physical Activity Following Phase II Rehabilitation: Protocol for a Mixed Method Randomized Controlled Pilot Study (ACTIVE-CaRe Pilot)

Background: Patients with cardiovascular disease (CVD) often encounter challenges in establishing and maintaining heart-healthy physical activity habits, even after successfully completing a cardiac rehabilitation program. Digital health technologies hold promise to support long-term habit formation in the secondary prevention of CVD. The aktivplan digital health intervention has been developed to support patients with CVD in establishing long-term heart-healthy physical activity habits. Objective: The primary study aim is to pilot and assess thefeasibility of a future randomized controlled trial design to investigate the effectiveness of the aktivplan intervention and to assess the usability, user experience, and acceptance of the aktivplan app. The secondary objective is to collect clinical and safety outcomes. Methods: This multicenter, mixed method, randomized controlled pilot study aims to recruit 40 patients with an established diagnosis of CVD or with increased risk of CVD (physically inactive along with 1 further CVD risk factor) who are undergoing phase II rehabilitation at 2 rehabilitation centers in Austria. Participants will be allocated to the intervention or standard care control group by stratified randomization and will be monitored for 10 weeks after discharge from phase II rehabilitation. Participants, health care professionals, and outcome assessors are not masked (blinded) to group allocation. Data collection will include recruitment and drop-out rate; data completeness; adherence to the intervention; usability, user experience, and user acceptance questionnaires; technical reliability of the intervention; clinical assessments (exercise capacity, physical activity behavior, and CVD risk factors); adverse events; self-reported outcome measures (health-related quality of life, exercise self-efficacy, depression and anxiety, and kinesiophobia); patient interviews, and focus groups with health care professionals. Quantitative data will be analyzed descriptively, and 95% CIswill be calculated for recruitment and drop-out rates and for data completeness. No confirmatory inferential statistical analysis or hypothesis testing will be conducted. Qualitative data will be analyzed thematically by framework analysis. Results: A total of 34 participants were recruited between October 2023 and May 2024. Data collection was completed in August 2024. Currently, the data are being analyzed and prepared for publication. The first publication of feasibility results is expected by summer 2025. Conclusions: This pilot study is expected to generate valuable and comprehensive insights to inform the study design of a future definitive effectiveness trial of the aktivplan intervention, guide the need for further iteration of the aktivplan app before entering a definitive trial, and inform future implementation strategies for the intervention. Trial Registration: ClinicalTrials.gov NCT06025526; https://clinicaltrials.gov/study/NCT06025526 International Registered Report Identifier (IRRID): DERR1-10.2196/73704